I judge a bank's technology by how its customers fare on the night it fails, so I pay for rehearsal, recovery and a plain explanation before I pay for new features.
I am managing executive officer and chief technology officer of Shiomine Financial Group, a regional bank holding company listed on the Prime Market of the Tokyo Stock Exchange, and of its bank, Shiomine Bank, headquartered in Niigata. We hold ¥5.5 trillion of deposits for about 1.6 million customers through 126 branches. I lead our Systems Division and technology subsidiary, about 330 people alongside roughly 300 partner engineers, with technology spending of ¥14.2 billion in the year to March 2026. I report to our president, Hideaki Tsukigase, and present system risk to our board twice a year.
I began in April 1995 as a mainframe programmer at a systems integrator, and spent eleven months of 1997 in Niigata writing interest calculations for the deposit system this bank retired in May 2025. I then helped run an internet-only bank from its first months, where I was responsible for a seven-hour transfer outage in 2008, and rebuilt card authorisation and fraud controls at a card company. Shiomine recruited me in 2016 to decide what should replace its own mainframe.
The answer was to join Kaname, a core banking system shared by nine regional banks and operated by Mikage Information Systems. Most of my work since has followed from that choice: when to move 3.4 million accounts, how to keep what the engineers who built the old system knew, how far to rely on public cloud within the Financial Services Agency's expectations, how quickly we can restore after an attack and which payment services a regional bank should still run itself. I have changed my mind on several of them, and the pages that follow say where.
A migration moved by four months
When our third full rehearsal in October 2024 found interest differences on 19,600 time deposits and an overrunning night batch, I recommended moving cut-over from January to Golden Week 2025. The delay cost ¥2.3 billion. Every branch opened on time on its first day on the new core.
Knowledge kept before it retired
Eleven re-employed mainframe engineers stayed on final pay until after cut-over, paid to explain rather than code. They recorded 2,140 business rules; 318 were in no specification and 27 would otherwise have been applied wrongly.
Recovery measured rather than assumed
Our continuity plan promised twelve hours to restore critical systems after an attack. An isolated test in 2023 took 61. After we separated backups and administrative accounts from production, the 2025 test took 9 hours 40 minutes.
A payment app closed deliberately
We closed our own smartphone payment app in March 2026, returning 97.6% of balances automatically and moving the prefecture's voucher programme to a widely used service. The bank saves about ¥380 million a year.
Current focus
I am proposing to the Kaname member banks the first exercise in which all nine switch to the backup data centre together, rather than one at a time. I am also planning to move our internet banking front end to public cloud in 2027, but only once we have rebuilt it in our own data centre from exported configuration.
Conversations I welcome
I am not seeking another executive role. With our president's approval and a conflict review, I would accept one outside directorship at a listed company outside banking and outside our lending area, where the board wants technology risk questioned closely. I also accept occasional advisory and speaking requests.
